Vehicle speed control system



2 Sheets-Sheet l J. C. KEETON ET AL VEHICLE SPEED CONTROL SYSTEM Oct. 20, 1953 Filed June :28, 1949 QN SS .m l l L r I I m MR, ,w NJ

Oct. 20, 1953 J. c. KEETON ET AL VEHICLE SPEED CONTROL SYSTEM 2 Sheets-Sheet Filed June 28, 1949 Q 5 Mms wd mmm. .,m w 16.5. @a A e y MM ,M Y B Lmmum Patented Oct. 20, 1953 STAI-Esci?retenir OE F [El VEHICLE 'SPEEDCDNTROL SYSTEMI .amesiGnKeet'onand Edgar B'.y Cones;l

17 Claims. i; (Cl. l

This' inventionrelates Ato vehicle speed control systemsf-more*particularly to systems'vand ap-IV`- paratus forautomatically controllin'gl'the speed` of Vehicles 'duri-ngfoperation in restricted speedWV zones along ahighway; Aand theinvention'hasffor 5r an object the-provision of improved ysystems-and i apparatus f of this ycharacterf- Vehicle speed control Aand traine Vcontrol sys.I temswliaveheretoforeJ been proposed'vwherein radio-eontrolledimeans*have been-"provided for #m producingtsuitablevisible or audible signalsfin they event that =thec vehicle exceeds the permise sible speedlimitfin thezoner or areain WhichLit is i',raveling;-anditv has-also Vbeen-proposed-to utilize Variousfmagnetically controlled devices for "15 automatically compelling vehiclesftoconfornrto the speed Jlimitations y-imposedx--in certainr` restricted f zones: e Such' l prior* arrangementsffhoweven have not been-found entirely -satisfactory^--l f in thatin some -cases cooperation ofthe-operator 2* of the vehicle `isfi'equ-ired-orlinithatlthe limitations" inevitably imposedby the use ofmagneticv elds andi-Y v magnetically-'1controlled idevicesf-hav`e -re sulted-in unreliable operation--v Accordingly'fity is eis-further objectief this inventicrrto provide" 25 improved; reliable and-inexpensive radio systems and; apparatus 1, .which -permitv the *Vehicles4 r"to operate:normally under the i' contrcvlfofA the-'oper atoroin zoneszof unrestricted speedeand which-f=fautomatically and-reliably 4Afunction `-to limitthe 35 speed-of the-vehicle in controlledzonesto the` v prescribed speed V'While "permitting normal operai-M- tion@ of thelvehiele' at lowerspeedsnf:

It isvavffurthenobject of the'invention to proef-fvide-ea vehiclerspeed .control system in which *g5 spaced.` apart .transmitting or controll stations arel providedat opposites-ends y-of a-restrictedf'speed zone'cfor transmitting `beams* of radio f-signals-"4 capable oi energizing vehicle-mountedspeedvconf h trol-means. as the vehicle passes the control sta;- o tionsriso as alternately to render =thefcontrol1-v means eiectivelor. ineffective to control` the fspeedffm'l of the vehicle;A

It is .anotheriobj eetl of` Athe invention tto provide" a system.-,of v the abovercharaeter inI which af zonef=45 of ordinary caution having a-mediu-mspeedf restrietionmayl contain. a; moreA limited Azone '-of extreme caution, having va Llower xspeed restriction-'-'- and: in'l which 'avehicle;I upon-entering-= the-ordi;K nary caution-zone; is limited to the"medium"5-0 speed;-'and-uponV entering'the "extreme caution' zone--is limitedto theOWer'speedso longas it remains -wvithin -the extreme caution. zone.

It is a stillfurther, object of' the inventionto provider a system of theiabove character'wherein y55 having "frequencies related tothe modulatingre- 2 y an emergency signal may be employed forstop 'g ping vehiclesioperating either Withinor vvithoutlM a speed control zone. Another objectof thieinvention-is the provision. of a'vehicle speedl control vsystem'wherein'low power, highifrequency transmitters are employd'" the carrier signals of which are modulatedwith??r distinguishable low. frequency signals determina: tive 'of the"particular-control Vfunctionto be achieved.`

Still",.another `object'of the"invention"i's the i provision of vehicle-mounted' speed control'ap-* para-tusioruse in systems of the*character^indi: cated and including;receiving.apparatusifor'iproc f ducing output signals distinctivelyrelatedto the' transmitted" signals `for "selectivelyeffecting theL desire'd'speed control;togettleriwith` speedcontro 'r f meansincluding capacitor'pr similar impedance" means variable fin accordance with" theispeedf'o the Vehicle;

In carrymgoutthe invention' in one'form,"a Vehicle speedzcontrolsy'stem is-*provided for auto-tr vl matically limiting the4` speedof vehicles vduring operation'in predetermined zonesalong 'thehighz Wayrwvhich 'comprseso'transmitter tmeansfdisposed adjacentthe highway and'=operative1 to transmitb'eams 'of' signalsv across-the highwayf'at oppositeendsoi the y'limited speed-zones; together with "vehiclemountedf receivingmeansoperative to receivethe" transmitted-J signals as the'Y vehicle entersand-ieaves thezones; normally ineffective speedcontrol means on the Vehicle adapted to be rendered effective' toA limit the f speed` of;- operationVw of the* 'vehiclefand' means energizable from" ther receivingimeans-during reception' of the trans= mitted signals foralternatelyrendering the Lspeed -f controliwmeans effective 'andA ineffective." More' specifically; thespeedv 'control' means includes :an impedance; `variable in accordance'with thespeed of the'vehicleyior causing-operation of the"s'peed^ control-*'-means at predetermined speeds during: i those-'intervals Whenthe 'speed' controlI means'has been rende-red effective; and additional 'imp'edx`-= f" ance means adjustable `to select --the iprecletere mined speeds-J at whiehthe speedcontrol means will ol'jerate.A -Preferably the 'transmittingmeans"e= comprisefloW-powerhigh-frequencytransmitters, the "carrier Vvvavesnf whichlareemodulated :at dierent'low frequencies indicative of the controlen" to be .exercisedahdz the'receiving'meanson the''t; vehicle i's operative vto produce. outputl signals el;

quenciesior "selectively controllingllapluralityf irelaylmeans, one ,of Whichr .upon alternate.` ener-.l glzations' thereof, renders the'speed control means effective or ineiective, and another of which is operative to adjust the impedance means which controls the speed at which the speed control means operates.

In addition to the above described zone control, the invention contemplates the provision of emergency control means comprising a similar transmitter modulated at a distinctive frequency, together with emergency control means'on the vehicle energizable from the receiver means and responsive only to output signals related to the modulating frequency of the emergency means for rendering the speed control means effective to prevent further operation of the vehicle.

For a more complete understanding of the invention reference may now be had to the drawings, in which:

Fig. 1 is a diagrammatic representation of a strip of highway including restricted speed zones and provided with spaced control stations or transmitting means embodying the present invention;

Fig. 2 is a diagrammatic representation of one of the transmitting units employed in Fig. 1;

Fig. 3 is a similar diagrammatic view of an emergency transmitting unit embodying the present invention; and

Fig. 4 is a somewhat schematic circuit diagram of vehicle-mounted receiving and speed controlling apparatus embodying the present invention.

Referring now to the drawings, the invention is shown in Fig. l as applied to a highway I9 which is divided, as shown, into a restricted speed zone requiring ordinary caution, indicated in Fig. 1 as a 30 M. P. H. zone within which is contained a more limited speed zone, such, for example, as av school zone, requiring extreme caution and indicated as a 15 M. P. H. zone. As shown in Fig. 1, a plurality of signal transmitting means or transmitting units II, I2, I3 and I4 are disposed adjacent the highway, the transmitting units i I and I 4 being respectively disposed at opposite ends of the 30 M. P. H. zone, and the transmitting units I2 and I3 being respectively disposed at opposite ends of the 15 M. P. H. zone. The transmitting units may be of identical construction and preferably constitute high or ultrahigh frequency crystal controlled signal generators of low power for transmitting beams of carrier waves that are adapted to be modulated with low frequency signals, preferably in the audio range.

As shown in Fig. 2, the transmitting unit I I, for example, comprises a 75 megacycle carrier wave generator I for supplying a 75 megacycle signal to a modulator and power amplifier unit I6, which is likewise supplied through a suitable double-pole double-throw switch I'I with a modulation signal of low frequency energy specically illustrated as a 442 cycle per second modulation signal generator I8. For purposes of exibility and for uniformity of manufacture, the transmitting unit II is likewise equipped with a 357 cycle per second modulation signal generator I9 adapted to be selectively connected to the modulator and power amplifier I through the switch I7. In the speed control system indicated in Fig. 1, it will be understood that the transmitting units I2, I3 and Id are identical with the unit II shown in Fig. 2, but in the units I2 and I3 the switch I'I occupies a position such that the 357 cycle per second modulation signal generator is connected to the modulator and power amplier. Thus, at opposite ends of the 30 M. P. H. zone the carrier wave signals beamed across the highways by the antennas of the transmitting units I I and I4 will be modulated at 442 cycles per second, while at the ends of the 15 M. P. H. zone the carrier wave signals will be modulated at 357 cycles per second.

In addition to the zone controlling transmitting units I I to Ill, inclusive, the present invention contemplates the provision of emergency control stations which may constitute police cars or ambulances equipped with transmitting units such, for example, as the unit 20 shown in Fig. 3, which are preferably provided with a '75 megacycle carrier wave generator 2|, a modulator and power amplifier 22, and a 210 cycle per second modulation signal generator 23 whereby the emergency transmitting units are operative to transmit a carrier wave of the same frequency as the Zone control units II to I 4, inclusive, but modulated at a different low frequency.

As will be more fully explained hereinafter, the present invention contemplates that vehicles operating on the highway I0, for example, shall be equipped with suitable receiving and speed control apparatus adapted to respond to the various signals transmitted at the control stations II to lf3, inclusive, and the emergency control station 2B in order to effect automatic speed limitation of the vehicle in accordance with the zone requirements or to effect automatic stopping of the vehicle under emergency conditions. Thus the arrangement is such that, as the vehicle traveling along the highway I from left to right in Fig. 1, for example, enters the 30 M. P. H. zone, the carrier wave radiated from the transmitting unit II y, will be picked up by the receiving apparatus on the vehicle and the resulting output signal from the receiving apparatus will render the speed control means effective to limit the speed of the vehicle to 30 M. P. H. Upon passing the control station I2, the carrier wave radiated by the transmitting unit I2 will be picked up by the receiver, and the resulting output signal from the receiver will adjust the speed control means so as to thereafter restrict the vehicle to operate below 15 M. P. H. Upon leaving the 15 M. P. H. zone, reception of the signal transmitted from the control station I3 is effective to readjust the speed control means on the vehicle to a 30 M. P.'H. limit, and upon leaving the 30 M. P. H. zone, reception of the signal from the control station I4 is effective to render the speed control means ineective thereafter to limit the speed of the vehicle. If at any time during its travel along the highway I0 emergency conditions arise such that an emergency signal is transmitted from a transmitting unit 2G mounted on a police car or ambulance in the immediate vicinity, reception of the emergency signal by the receiver apparatus on the vehicle will cause the speed control means to immediately render the vehicle incapable of further operation, thus bringing the vehicle to a stop and maintaining the vehicle in this inoperable condit1on so long as the emergency signal continues.

Referring now to Fig. 4, the receiver 25, which is provided with the usual antenna 26, is of a well known type capable of receiving the 75 megacycle carrier wave signals radiated by the transmitting units Il to III and 2S, and of detecting and demodulating these signals so as to produce in the output circuit of the receiver, signals having frequencies respectively related to the modulation frequencies of the carrier waves. Connected in parallel to the output circuit of the receiver 25 through suitable control tubes 21, 28 and 29, are a plurality of tuned or resonant relays 30, 3I and 32. which-are adaptegrtc respondonlyfte receiyeme: by -.ieitltzenneya-2nd5-e$i a193fAS :ier-a output signals 0f predeternriineclif lireeuencie theffiawipeeihis. leeedfplk Thuslas indicetedfinFig: 4thefoperatinewindna. a feed-bach typeT cscillater; 0f theureley 39 .isI connectedin a tuned ,Qircuitf ludeSl-er-dupleii dioflefpento l Whichyincludessa.suitable inductance 3,3 anda. 5 Capacitance 34 whichnwithfthe operatinsuwind; inarform 1e; tank. circuit atuned'to. alfrequencv ci 44:2r cycles nerasemmd f Smilarlm themperating: Windinaof thepreiayial, together.. -w-ithia-n indut ance35 and. @capacitance 3,6,ferm1a tank-Circuit le tuned-t0. resonance at 357:.cyc1eseperfreecondfandv thexoperatng Windingcf theyrelevil toeethel withfztheeinductance 3] and the;l capacitance .38, formz al tankvcrcuit.tunedetc resonance-fat 2110. Cycles-apen -sec.ond.. ,i .The energizing ',ftircuits 1 for :i5 the relaysl, f3 l and32 respectively extend froma sourceo. .energy `indicated as B-l-ithroueh-,the tank @inuit-andthe: associatedcontrol `tube 5to the:,otherside ofV tliesouree,of energyfby .Way v of faground conriecticns.3 9,f` and-it; willlbe vapparent 2o that t 1f1e;-l relays thus operate Ionlywhen.output ey.: signalslof the, proper l frequency .appearein the-:;-. output circuit of the receiver ,f

As shown .-,in Fig-w14, the `respective:contacts49,12 4l and 42 of the relays 30, 37| and 32 are arranged. 25

to complete energizing circuits forthe operating` impe e1 and -theqspee t Which- ,ythe relay. Windingsof additional relays-43,44 and 45..: The operatiorn-Qcciirs maygbe @climbed-by v lblieqf .5 energizing circuit forthenoperating Winding of additionalgimpedancescpntrollegljoy the relays. ai; thefrelay `A3 extends, as shown, from .a ground:A

connection 46 .through-thecontacts 40 4of the 3,0 ,q ,gto the oscillatoiirpiti6@,fjhe relay Sil/the operating :winding of the relay 43,.; l pented `sec tienfgf thetub fill Whi h ,C nstitulte and by way of the conductors 4l, 48,.',49 and 5t the sensitiyeelemento therelay,Qililfrnllidc andtheignition vsvvitch 5| of the vehicle to one an anedeor plategg Whichjs connected ,through side of the vehicle batteryv 52and from the other the-;conductors 8 5, ,-86, 8 1 and to onegof side of the battery 52 to the ground connection 35 contazztsititA on thegelay 4 3,t he-oth er they 53. .Similarly, the energizing. oircuitforthe relay tactsf-BI beingonne c t e gto a sour t elegend B,-{-:.-.

44 extends from theground-.connection Mythe voltage, lidiatedzbl W l, contacts 4l of the relay 3l theI operating winding tionnthepentodgsection oi the tube--lg includes of the `relay 44, and by way of aconductor 55 to the usual suppressor grid 89 connecte the conductor43,..froniv whence it extends to 40 eathodeysanda sreengridygl Whig ground as in the previously,describedenergizing nected-tliroiighacholegoil 2 circuit. Likewise, the Venergizing circuit for, the torsil and 8 5 te theplateqhand 5,; ley-10355. relayv 45 extends from the groundconnection 5,6 in accordance' With-,conventionalkb ac ticenby through the contacts42 of the'relayz32 and the condenSQlfrS. operating winding of the relay 45, to thefconducf, 45 The Qscill orcircuitl includes agi'mk Sill Q14' tor 49 and thence to ground through the remainl comprising an Aindustance; 9 5 AligtvingyatagI 5,6 to der; of the .previously traced energizingcircuitsxwhich-thecathode' 3G connectedyand a. con;

The relay 43,',Which may llee Iof any .-typefvvell-y 'z denser 1,91 onegterminalof thetanllcircuitlgeing knownin the art capable, on successivefenergizae, a connectedthrough a gridgcondenserf. 8 'ftp 7th tions; of alternately openingand closing; elf-paire@ ccm-,m1 vgrid .9 9 o f the Age-npr)de,serai-irai: Qf ,the, of contacts, is shown as comprising aratchettypa d tubef, thegnsual grid-leal;- resietoryl Qigeldgplt relay having an armature 51 adapted,-each time l l blockingieondenser llbeing connected-as showthat the WindingV of the relay 43 ,is energized, Thepentodepower amplglzubezl 1.1014 to advancea ratchet wheel through .one step, f a platerrllf;monnectedg, through @hei-opera and .-.the ratchet Wheel, as .indicated by the .55 Winding vof the relay l2 andt l1econdii ctors3lfl3, u broken line4 59,is connected to drive a suitable I04,493,58m-.181388 andgthee contacthsl Tof thier contact,y operating cam or drum E0 so as alterrelayg143, :to asource of pla-teg:voltagev B+; ,and natelyto open and close a pair of contacts 6I. s the 'cathodel o f theapowerampliflerll is con Similarly, the relay 44 is shown as comprising an nectedilthrough an adjustableycathode resisto` armature 52 adapted to operatea'ratchet Wheel -60 L06 and why-passing ycondenser l'|to grot-1nd,,at 63, which. drives a contact operating drumor Y l08.@Thezsuppressortgrid AI Elof thetubell i` cam.. 64 so as alternately to engage a movable connecteddigrectlyfto thelcathodathe s creengri contact.. .65 vwith one. or the Votherof a pairof i III] is,connecte'd1-throughthegconductoryllhan spaced contacts 66 and 6l.y Therelay 45, on the the fprevouslyftraced-, circuit @to theffsourceyof other hand, is of a conventional normally open 65 s reenuegrid:Voltage.fandzfthefcontrol;grid V|.'|2.; is type having a pair of contacts 68 adapted. to be connected-throughthe usualjbyepass;condense closedr whenever the operating winding-of the H3 and gv eL-.leale resistor llfllQ ground, at .Ig relay4 45 is energized and to openas soonras the- As shown, n the;drawingsgthecontrol grid |2- operating Winding. is deenergiz'ed..` of the-taupe 1, l is c onnectectlpy :means ef vaycon 'Ine-speed controlineansl of the present inven-O duCDI' 14551313 'Ghlaplalesglll of the. diodesectio tion which .is associated with 1and operated -by t 0f thezpeniggeztubleffl,'.theplatestlgloeing een the various relaysiunder .the contrclfof there necteeain eerellelfes Theldiosielcircuitceiver 25, constitutes a capacity operatedrelay l which is efeftiierto igmpQSe-Qnthecontrelgri of the; generaltynedescribed at paeesyeland 5050i the textlieok,eEleetrQn-flubesin Indtustrxn'h ming on the cathode su of the tube 1o, extends from the plates I I6 to the cathode 9|! and by way of the portion of the inductance 95 Ibelow the tap 96 in the tank circuit to ya junction point II'I. From the junction point I I1 a plurality of alternative paths to ground are provided which include the parallel arranged sensitivity control resistors H8, H9 and |20 and the relay contacts '66, 61 yand 468, the diode circuit being completed from 'the ground connection |08 by way of the grid condenser H3, the grid leak resistance H4 and the conductor II5 to the diode plate H6.

In general, the operation of the speed control means thus far described is such that the biasing potential vapplied to the grid I I2 of the power amplier tube II is 'dependent upon the operating condition, i. e. the intensity o-f oscillation, of the oscillator 69, and the adjustment of the sensitivity resistors H8, H9 and |20. n order to control the oscillator B3 in accordance with the speed of the vehicle, variable impedance means are provided comprising a condenser associated with the speedometer |23 of the vehicle and, as shown in Fig. 4, including a stationary condenser plate I 2| and a movable plate |22 which is carried by the shaft of the speedometer 23 and adapted to be moved relative to the plate I 2| so 'as to vary the relative capacity thereof. As shown, the movable plate |22 is connected to ground at |24, While the stationary condenser plate I2I is connected by Way of a conductor |25 to the control `grid 99 of the tube 10. The intensity of oscillation is thus caused to vary with changes in the capacity to ground provided by the speedometer controlled condenser, and, as more fully explained hereinafter, the sensitivity of the circuit may be adjusted by the sensitivity resistors I I8, I I9 and |20 through which the cathode 99 is connected to ground.

With the Aforegoing description of the various components of the receiving and speed controlling apparatus in mind, it is though that a complete understanding of the invention may best be had from a description of the operation of the apparatus under various conditions. assumed that the vehicle upon which the apparatus shown in Fig. 4 is mounted is moving down the highway I as previously described ata speed less than 30 M. P. I-I., and enters the 30 M. P. H. zone at theV control station II. Thereupon the receiver 25 will produce in its output circuit an output signal having a frequency of 442 cycles per second so as eiectively to energize the relay 30, thereby closing the previously traced energizing circuit for the operating Winding of the ratchet type relay 43. Upon the consequent operation of the armature 5'! of the relay 43, the ratchet wheel 58 and the cam 6I) will be advanced one step so as to close the contacts 3| and thereby apply plate voltage to the tube 'Ill of the oscillator -69 and to the power amplier I I. Oscillation at a high yamplitude and at a frequency determined by the constants of the oscillator circuit will thereupon be generated in the oscillator circuit 69, and as previously indicated, a rectified current proportional to the high frequency potential on the cathode 96 will be caused to dow through the previously traced diode circuit, including the sensitivity resistor H8 `and the contacts 66 and 65 of the relay 44, the Contact 65 being in the upper position shown in the drawing. This rectified current will, by virtue of the grid condenser I I3 and the grid leak resistor I I4, impose a sufficient negative bias on the control grid H2 of the amplier 1I to bias the amplier It will be y Y tube beyond cutoff and consequently the relay I2 will not be operated.

If, however, the speed of the vehicle is now increased to 30 M. P. H. thereby moving the condenser plate |22 relative to the stationary condenser plate I2I so as to increase the capacity to ground provided by the speedometer-operated condenser, the intensity of oscillation in the oscillator 69 and accordingly the potential o-f the cathode S0 will decrease, thereby decreasing the negative bias applied to the grid I I2 of the power amplifier 'H from the oscillator circuit so as to decrease the bias of the tube Il below cutoi. The consequent flow of plate current through the power amplifier 1| effects operation of the contacts 'I3 of the relay 'I2 to complete an energizing circuit for the relay 74, which energizing circuit extends from the ground connection 53, the battery 52, the ignition switch 5I, the conductors 50, 'I9 and |25, the contact 73, the conductor I`2I and the operating Winding of the relay 'I4 to the ground connection |28. The relay 'I4 thereupon operates to open the contacts 'I5 :and thereby interrupt the ignition vcircuit of the vehicle.

Thus the speed of the vehicle will be prevented from increasing above 30 M. P. H. and as soon as the vehicle slows down to a speed of approximately 26 M. P. H. the consequent variation of the speedometer-operated capacitor will so affect the condition of the oscillator 63 as again to bias the power amplifier beyond cutoff, thereby deenergizing the relays 'I2 and 14 so as to reestablich the ignition circuit to again allow the vehicle propelling means to resume operation.

It will, of course, be understood that if the vehicle at the time it enters the 30 M. P. H. zone is operating at a speed above 30 M. P. H. so that the speedometer-controlled capacitor is at a maximum value, the amplier tube 1I will not be biased beyond cutoff by the oscillator and current will immediately ilow in the plate circuit of the amplifier so as to energize the relays 'I2 and '.i., thereby opening the ignition circuit and preventing further operation of the Vehicle propelling means until the vehicle speed has dropped to a valve below 30 M. P. H. While the relay 'I4 has been shown as controlling the ignition circuit of the vehicle, it will be apparent that this relay may, if desired, be arranged to control the supply of fuel to the propelling means so as similarly to render the propelling means capable or incapable or operation.

When the Vehicle passing through the 30 M. P. H. zone reaches the beginning of the 15 M. P. H. zone, the receiver 25 on the vehicle will pick up the modulated carrier transmitted from the control station I2 and will consequently produce in its output circuit an output signal having a frequency o1^ 357 cycles per second, thereby effectively energizing the tuned relay 3| to effect operation of the ratchet type relay |34. Operation of the ratchet wheel 63 and the cani wheel 65 of this relay is eective to open the contacts 65 and 68 and to close the contacts e5 and 6l, thereby eliminating the sensitivity resistor H8 from the previously'y traced diode circuit and substituting in its place the sensitivity resistor I I9 which is of lower resistance. Due to the decreased resistance thereby connected between the cathode 3G and ground, the potential of the cathode to ground is decreased so 'as to impose on the grid H2 of the power amplifier 1I a lower negative bias. The sensitivity of the capacity controlled oscillator and power amplier thus increases to a point at which operation of the resafcsegooa laysl 12- and 'I4 to-interruptsthe ignition-circuit 'will' occur at alower`-effective'capacity ofthe fspeedometer-controlled" condensen'i. e. when the condenserreaches a positiondcorresponding to 1.5 M. P. H. Thus theespeed of the'vehicle will be limited to 15 M. P. H. until such time "as the vehicle passes fthe control station I3, whereupon the ratchet type relay willfagain beoperated to movethe ratchetwheekand-thefcam Gflone step l so as to openY the contacts 654-43? and-reclose the contactsA 65'-E6, v thereby restoringv thee-sensitivity resistor- IIB to the circuit and v-againpermitting the Vehicle tooperate up to 30 M. P. H. As soon as vthe Vehicle passes -out of 'the 30 M. P. Hzone, a signal received `from-the control station I4 will effect energization of-theratchet type relay 43, thereby'openingL--the'contacts 6I so as to removeplate voltage from thetubes 1B l and 1I, thereby rendering the controlmeans in- -effective so th'at `thevehicle `may be operated at anyvdesired -speedvregardless of-*the position to` which the--speedometer-controlled capacitor is moved If at any timeduring theoperation of the ve- -hicle a signal is transmitted fromethe--emergency control station-comprising ythe transmitter unit 20, `thereceiver 25,-'upon 'receiving thc carrier wavefrom the unit 20,Will produce in its output circuit a signal having la frequency off-2l()Y cycles per'second, thereby energizing the tuned'relay 32 I to eiect energiZa-tion'of the relay l5 as heretofore explained. In additionthe contacts*` i3@ ofthe relay 32 will be closed so as to; apply plate voltage from-the sour-ce Bel-"throughthe conductor I3Il to'the'tubes Hl-'and ,'II, thereby rendering the speed control means effective, the Asame as upon-closure of vthe` contacts 6l of the'rat'chet 'A inhthecathode'circuit of the oscillator till either lalone or in pa'rallelwith'one or-'theother of the sensitivity'resistors* I I B and i I I9 depending upon ZWhetherftheVehiCle was operating in an unrestricted Zone,a 30 M. P. H. zone'or a l5 M. P. I-I. A"Zone at the time of the-emergency nsignal.

1- 10 a 30 M. P. H. zone, this'may beeiected--merely by' addingA an additional`v` set ofcontacts to the relafy' 44v adaptedV for operation by the cam 64 land arranged to apply and remove plate voltage to and fromthe tubes Ill and H at alternate operations of the relay 44.

'While particular embodiments of :the invention have been shown, it will be understood, of course,

that Vthe invention is not limited thereto since many modiiications may be made andA it istherefore contemplated by the appended claims to cover Vany suchmodications as fallwithin the true spirit andscope of the invention.

v"What is claimed and desired to begsecured by Letters Patent is:

.1. Avehicle speed 'control system for automatically limiting the vspeed of vehicles during Aoperation in predetermined zones along a highwaycomprising,'a plurality of low-power Vhigh-frequency transmitters locatedadjacent oppositeends of 4said zones and operative continuously to .transmit beams of high-frequency signalsacrossv said highway independently of vehicle movement on said' highway, said' transmitters including means for modulating' diierent ones ofjsaidbeams at different low frequencies indicative of tliecdegree of speed control to be exercised in said zones, vehicle-mounted Xedtuned receiving meansoperative to'receive said modulated.high.frequency signals and to produce, output., signals .having frequencies respectively .related to said `.I'nod'ulating frequencies, normally ineffective speedcontrol means on said vehiclesadapted to. berendered eifective tolmitl the speed ofoperation of 43.: Closure ofA thev contacts 58 ofthe relay E5 is H eifective to*co.nnect'theA sensitivity resistor "I'EEI q said'vehicles, said speed Vcontrol means .including means for varying the maximum speedpermitted thereby, and a plurality of tuned-relay means energizalclev from said receiving meansgand "respectively, responsive to output'. signals of. dif- This resistor vI2I is` so proportioned that'fthe sensitivity of the Ica'pacity-controlled oscillator If it is ldesired to provide a systemwherein l emergency control ofthe vehicle can be'ac'com- 'plished only when Ythe'vehicle is operating in a limitedA speed.v control' zone, -it isI necessary only to eliminate thev contacts I3ll on the relay 32,` where- Aupon'operation ofl the relay 32 bythe emergency I control signalwill be effective only if'rthe ratchet vtype relay 43 vhas previously been operated to apply plate voltage to the tubes 'IB 'and 'l I :Pimi- -larly if it is desi-red toprovideaI system'having a 15 M. P. H. zone which is-'not-containedwithin and amplifier kis'increased to 'a'point where` the capacity ofthe speedometer wiring to ground g 'issuicient to decrease 'the intensity of'oscilla- ,"'tion to a'point permitting the flow of'current v-throughtheamplifier l'I,-thereby to` operate the Aferent frequency for rendering.saidspeed-.control means alternately effective orineff'ectiveandr for varying saidmaximum speed.

2. A vvehiclerspeed control system-,forA :auto- Amatically limiting the speed of Vehicles during operation in predeterminedzones. along al highway. comprising, transmitter means-adj acentf said highway operative v continuously-i to vtransmit .beams ofk signals across said-highway atppposite ends of said zones -independently of` vehiclemovement on said highway, vehicle-mounted receiving means operative to receivey said signals as said jvehicles enter and-v leave said zonesnormally. in-

5 eifective speed control means on. said-. vehi c1es adapted'to be rendered effective to limitthespeed of ,operation of said., vehicles, said. speedfcontrol means includingl an impedance variable infaccordance withrthe speed of said-vehicle forecaus- ,ing operation of said speed controlmeans aupredetermined speeds. `during intervals--whemsaid `speed. control means is effectivdandmeans energ'izable from said receiving mear-isuponfreception of said signalsrfor alternately renderinglfsaid speed controlmeans effective or. ineiective.

3. A, vehicle speed. control .systemArvfor automatically limiting the speed of vehiclesduring operation in predetermined zones along'a.,-.high

iway comprisinga plurality oflow-,powenhighfrequency transmitters located adjacentpposite ends of said zones and operativecontinuously to transmit beams of high-frequencyl signals across said vhighway. independently 'of vehicle. movement on said highway, vehicle-mounted V.Xetl-tuned receiving means operative to. receivesaid, signals as said vehicles enteruandleavesaid,zones-,and

to produceioutput control signals therefrom, normally ineffective speed control means on said vehicle adapted to be rendered effective to limit the speed of operation of said vehicle, said speed control means including an impedance variable in accordance with the speed of said vehicle for causing said speed control means to operate at predetermined speeds during intervals when said speed control means is effective, and means energizable by said control signals for alternately rendering said speed control means eifective or ineective.

4. A vehicle speed control system for automatically limiting the speed of vehicles during operation in predetermined Zones along a highway comprising, transmitter means adjacent said highway operative to transmit beams of signals across said highway at opposite ends of said zones, vehicle-mounted receiving means operative to receive said signals as said vehicles enter and leave said zones, normally ineffective speed control means on said vehicles adapted to be rendered effective to limit the speed of operation of said vehicles, said speed control means including capacitor means variable in accordance with the speed of said vehicle for causing operation of said speed control means at predetermined speeds during intervals when said speed control means is effective, and means energizable from said receiving means upon reception oi said signals for alternately rendering said speed control means effective or ineffective.

5. A vehicle speed control system for automatically limiting the speed of vehicles during operation in predetermined zones along a highway comprising, a plurality of low-power highfrequency transmitters located adjacent opposite ends of said zones and operative continuously to transmit beams of high-frequency signals across said highway independently of vehicle movement on said highway, said transmitters including means for modulating diiferent ones of said beams at different low frequencies indicative of the degree of speed control to be exercised in said zones, vehicle-mounted fixed-tuned receiving means operative to receive said modulated high frequency signals and to produce output signals having frequencies respectively related to said modulating frequencies, normally ineffective speed control means on said vehicles adapted to be rendered e'ective to limit the speed of operation of said vehicles, said speed control means including impedance means variable in accordance with the speed of said vehicle for causing operation of said speed control means at predetermined speeds during intervals when said speed control means is effective and also including other impedance means adjustable to select said predetermined speeds, and a plurality of tuned relay means energizable from said receiving means and respectively responsive to output signals of different frequency, one of said relay means being eiective on alternate energizations thereof to render said control means effective or ineffective and others of said relay means being effective upon energization thereof to adjust said other impedance means.

6. A vehicle speed control system for automatically limiting the speed of vehicles during operation in predetermined zones along a highway comprising, a plurality of low-power highfrequency transmitters located adjacent opposite ends of said zones and operative continuously to transmit beams of high-frequency signals across said highway independently of vehicle movement on said highway, vehicle-mounted fixed-tuned receiving means operative to receive said signals as said vehicles enter and leave said zones and to produce output control signals therefrom, normally ineffective speed control means on said vehicle adapte-d to be rendered effective to limit the speed of operation of said vehicle, said speed control means including an impedance variable in accordance with the speed of said vehicle for causing said speed control means to operate at predetermined speeds during intervals when said speed control means is effective, and also including other impedance means adjustable to select said predetermined speeds, and means energizable by said control signals for rendering said speed control means alternately effective or ineffective and for adjusting said other impedance means.

7. A vehicle speed control system for autematically limiting the speed of vehicles during operation in predetermined zones along a highway comprising, transmitter means adjacent said highway operative continuously to transmit beams of signals across said highway at opposite ends of said Zones independently of vehicle movement on said highway, vehiclemounted receiving means operative to receive said signals as said vehicles enter and leave said Zones, speed control means on said vehicles for limiting the speed of operation thereof, said speed control means including normally deenergized oscillator means and relay means responsive to a predetermined operating condition of said oscillator means to limit said speed, means energized from said receiving means during successive receptions of said signals for alternately energizing and deenergizing said oscillator means, and impedance means connected in circuit with said oscillator means and variable in accordance with the speed of said vehicle for varying said operating condition when said oscillator means is energized to cause operation of said relay means at predeterrrned speeds.

8. A vehicle speed control system for automatically limiting the speed of vehicles during operation through a iirst zone of ordinary caution within which is contained a second zone of extreme caution, comprising a plurality of wave signal transmitters spaced along said highway and respectively located at opposite ends of said zones and operative continuously to transmit beams of signals across said highway independently of vehicle movement on said highway, said beams of signals at said opposite ends of said rst zone being distinguishable from said beams of signals at said opposite ends of said second zone, vehicle-mounted fixed-tuned receiver means operative to receive said beams of signals as said vehicles enter and leave said zones and to produce output signals respectively distinctively related to said distinguishable beam signals, normally ineffective speed control means on said vehicles adapted to be rendered eiTectiVe to limit the speed of the vehicles and including means adjustable to vary the maximum vehicle speed permitted by said speed control means, means energizable from said receiving means and responsive only to output signals distinctively related to carrier beam signals at opposite ends of said first zone for rendering said speed control means alternately effective and ineffective, and other means energizable from said receiving means and responsive only to output signals distinctively related to said beam signals at opposite ends of said second Zone for alternately operating said adjustable means to vary Jil-'22,656,002

i13 saidmaximumspeed betvveen-V limits corresponding tos'saidzfirst. and'second Zones.

9. Ailvehicle speedcontrol system 'for automatically limitingthe speed of vehicles during operation through a first zone of :ordinary cauf,-;.tion Withintwhich is contained a second :'Zone of lextreme :,caution, comprising a plurality of iwave' signaly transmitters spaced alongv said highxway and respectively located atv opposite ends ff of. said zones andoperative continuously'to trans- ;::'mit beams of signals'facross said `highway infzdependently of'vehicle movement onV said high- Wayrsaid beams of. signals at said opposite ends yf ofsaidvfirst V.zone beingdistinguishable from said beams of signals at -said opposite ends of'said =";11second zone; .Vehicle-amounted fixed-tuned receiver means operative to receive said .beams of signals as said vehicles enter and leave said 5, vzonesfand to produce output signals'fhaving fre- :quencies respectively distinctively related tosaid distinguishable beam'signals normally ineffectivespeed control means on said vehicles adapted to. berendered effective toY limit the .speed of 5.1.;the vehiclesandincluding means adjustable to *.varyfthe maximumyehicle speed permitted by 'ii-said speed vcontrol means, tuned relay means :energizable from said receiving meansr and responsive' only tol output signals of frequencies distinctivelylrelated to carrier beam signals at 1 foppositeends of= said rst zone for rendering said speed control means, alternately eiective and ineiective,Y ,and :other `tuned relay means energizable fromsaid receiving means and respon- 'sive only, tofoutputsignals. having frequencies i 1: distinctively related to said `beam signals at opposite ends 0f said second zone for alternately .operating said "adjustable-means to vary said i fimaximumspeed between rlimits corresponding to esaid rst and second-zones.

Y l l0. A vehiclel 'speed control .systemvfor autor.,,-matically.1imiting. the'speed of .vehicles during operation'througha rst zone of ordinary caution within'which is contained a second Zone of extreme caution,:comprising aplurality of wave '.signal'ltransmitters spaced along said highway and respectively-located at opposite ends of said y; `zones andI operativev continuously to transmit beams of isigna'lsacross said highway independently of vehicle1movement on said highwaysaid r-f beams offsignals atsaidopposite ends of-said ixrst zonebeing. distinguishable from saidhbeams of signals atsaidaoppositeends of saidisecond zone, vehiclelmounted:fixed-tuned receiver means f 'operative toireceive said beams ofiA signals as said vehicles 'entere and leavesaid Zonesrand to1proifwzduceeoutput.. signals respectively distinctively a, :related to said `distinguisllablel beamv signals', normally inefiectivepspeed control means on said vehcl'esadapted to be rendered eiective to limit the speed of the vehicles, said speed control.

-means vincluding impedancefmeansfvariable in. accordancex-With the-speed offsaid vehicle for causing operation of said speed control means at predetermined speeds during. intervals when-said speed control'means isv` effective and. also. in-v cluding means radjustable to vary sadvpredeterminedvehicle'speedpermitted by saidspeed control means, means energizable from said receivinglmeans and responsive lonly to outputsignals distinctively related tor carrier beamy signals at@ opposite .ends of said first ione for vrendering Y said speed control meansalternately #effective .and ineffective, and otherl means-energizable from said receiving meansand responsive only to output signals distinctively related to said ,.maticallylimiting-the speed of vehicles-:during operation througha first zone of ordinaryicauv- -tion'- within: which is-Y contained a second' zone ofv extreme .caution-comprising a-plurality: of Wave signal transmitters spacedalongsaid high- Way and f .respectively located at `opposite ends of said zones and operative to-transmitvbeams of signals across f said` highway, f said -beams of;l signals at said Yopposite-ends ofsaidrst zonebeing s distinguishable from -saidv beams of signalsi at '-said-opposite ends of said 'second zoneyavehicle- :mounted 1 iXed-tuned receiver 'means operative to receivesaidfbeams of; signals as saidevehicles i enter` and', leave saidzones `and to producefoutput signals of affrequencyrespectively distinctively related-to said distinguishable beam signalsfnors. mally ineffective speed control means on-said vexzrhicles-adapted to be rendered Ieiiective toil-imit Vthespeed of thet vehicles, said `speed -;.control f meansv includingl capacitor means variable in-.ac- :i cordanoe `with the-,vehicle speed forcausingf-.op- .aeration of said-speed-ccntrol means alt-:predeterx mined speeds during intervals when -said ffspeed control means is eiectiveand also including-impedance -means adjustable to varysaid -predetermined speed at which -said speedcontrolfmeans is .l operated; ltuned relay :means energizablefrom said receiving means and responsive onlyA toi-output rsignalsv of ja' frequency--distinctively frelated` to carrier -beam signals atoppositeends of :said V'11"1rst'v-azone. for rendering said -v speed control 'f means alternately effectiveand ineffectiveend v othery .tuned 'relay'. means` energizable' from said l10i-'receiving Ymeans andfresponsive-` only to-output signals of a frequencydistinctivelyfrelated to said` beam signals atfoppositeends offsaid second azonezffor alternately voperatingffsaid adjustable `"impedance-meansv to.. vary said predetermined speed betweerrlimits .corresponding toysaidf-.rst z; andsecond zones.

12. -A-highway `traiic'controly system 4for-.fautopimatically limiting; the-speed of vehicles; during zgr'operation lthrough .a `rst yzone of-ordinaryrcau- 50 tion-within `which isl contained-fa 'second-Zone of f extreme caution;E comprising; aiplurality loftrans- 'mitters spacedalong said highwaya 'and urespectivelylocated atopposite ends of` saidzones and '-;-:-operativecontinuonsly toatransmit beams of'carrier wave signals across ;.said-- highway independently of vehicle movementY onf said 'highwaysaid Hf-transmitters atsaid opposite ends of sadrst `zone inoludingmeans for modulatingv said vcarrier 11W-ave. signals at .az'rst Ilow-frequency andfsaid --etransmitters at. said :opposite 'ends of: saiclffsecond :zone including,r means for modulating saidfcarrier Wave signals at ai second lovv` frequency, vehiclemountedfXed-:tuned':receiver meansfoperative to receive said 'modulated'carrier Wavef signals as said. vehicles zenterfand'leave said zones and to riproduce, voutputffsignalsf` having frequencies Vfrespe'ctively.- related to? said'rst and-second` low fre- Iend u-oncies; iinormally ineffective Y, speed- Tcontrol means on said vehicles adapted to be rendered :effective tolimitfthe speed' of saidvehicle and :.including ymeans adjustable to vary the maxif.z-;;mumavehiele speed ypermitted by said speed controlemeans, means energizable lfrom saidsreceiving meansand iresponsive `only to said-foutput signals of a frequency related to said rst 10W frequency for rendering said speed control means alternately effective and ineffective, and other means energizable fromy said receiving means and responsive only to said output signals of a frequency related to said second low frequency for alternately operating said adjustable means to vary said maximum speed between limits corresponding to said rst and second zones.

13. Wave signal responsive vehicle speed control apparatus for use in traine control systems of the type including a plurality of low-power high-frequency transmitters operative continuously to transmit distinctively modulated carrier Wave signals, comprising Xed-tuned Wave signal receiving means operative to receive said carrier Wave signals and to produce output signals having frequencies respectively related to said distinctively modulated signals, normally ineffective speed control means operative when rendered effective to limit the speed of the vehicle by temporarily disabling the propelling means therefor Whenever the vehicle attains a predetermined speed while permitting operation of said propelling means at lower speeds, said speed control means including impedance means variable in accordance With the vehicle speed for causing operation of said speed control means at said predetermined speed when said speed control means has been rendered eiiective and also including other impedance means adjustable to vary said predetermined speed, means responsive to successive output signals of one frequency for alternately rendering said speed control means effective or ineffective, and second means responsive to output signals of another frequency for adjusting said other impedance means.

14. Wave signal responsive vehicle speed control apparatus for use in traflic control systems of the type including a plurality of low-power high-frequency transmitters operative continuously tc transmit distinctively modulated carrier Wave signals, comprising fixed-tuned Wave signal receiving means operative to receive said carrier wave signals and to produce output signals having frequencies respectively related to said distinctively modulated signals, normally ineffective speed control means operative When rendered efective to limit the speed of the Vehicle by temporarily disabling the propelling means therefor Whenever the vehicle attains a predetermined speed While permitting operation of said propelling means at lower speeds, said speed control means including impedance means variable in accordance with the vehicle speed for causing, operation of said speed control means at said predetermined speed when said speed control means has been rendered eiective and also including other impedance means adjustable to vary said predetermined speed, means responsive to successive output signals of one frequency for alternately rendering said speed control means eiective or ineiective, second means responsive to output signals of another frequency for adjusting said other impedance means, and emergency means responsive to output signals of a third frequency for causing said speed control means to disable said propelling means regardless of the speed of operation of said vehicle.

l5. A vehicle speed control system for automatically limiting the speed of vehicles during operation through Zones along a path of travel comprising, transmitter means operative continuously to transmit beams or signals across said path of tr-avel at opposite ends of said zones independently of vehicle movement along said path of travel, the transmitter associated With each ci said zones having a characteristic propagated signal, vehicle-mounted receiving means operative to receive said signals as said vehicles enter and leave said zones, means controlled in accordance with the characteristics or" the signals received by the receiving means for selectively establishing a iirst parameter condition, means responsive to the speed of the vehicles for establishing a second parameter condition, 4and means controlled in accordance with a comparisen of said rst and second parameter conditions for controlling the speed of said vehicles.

l5. A vehicle speed control system for automatically limiting the speed of vehicles during operation threugh zones aiong .a path of travel comprising, transmitter means operative continuously to transmit beams of signals across said path ci travel at opposite ends of said zones independently of vehicl movement aicng said path of travel, the transmitter associated with each of said Zones having a characteristic propagated signal, vehicle-mounted receiving means operative to receive said signals as said vehicles enter leave said zones, means on said vehicles for limiting the speed of said vehicles to predeterned speeds, means responsive to said received signals for selecting one of said predetermined for producing a particular parameter upon the *chicles attaining said selected one of said predetermined s eeds, and means responsive to said particular parameter for operating said speed cent1-ol means.

i7. A vehicle speed control system for automatically limiting the speed of vehicles during operation through zones along a path of travel comprising, transmitter means operative continuouslj,7 to transmit beams of signals across said path of travel at opposite ends or said zones independently of vehicle movement along said path of travel, the transmitter associated With each of said rsones having a characteristic propagated signal, vehicle-mounted receiving means operative to receive said signals as said vehicles enter and leave said zones, electrically1 responsive means on said vehicles for controlling the speed thereof, means controlled in accordance with the characteristics or the signals received for conditioning said speed controlling means to respond to different levels of control, means responsive to the speed of said vehicles for producing diierent control levels, and means responsive to the attainment of said diierent control levels for causing response of said speed controlling means.

JAMES C. KEETON. EDGAR B. CONES.

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